The present invention relates to clutch plates or clutch disc arrangements, especially to improvements in clutch plates for use in friction clutches. More particularly, the invention relates to improvements in clutch plates of the type wherein one component (including a clutch disc with one or more friction facings) is rotatable within limits relative to another component (including a hub) and/or vice versa, and wherein the relative angular displacement of the two components takes place against the opposition of one or more energy storing devices. Still more particularly, the invention relates to improvements in clutch plates of the type wherein a first stage of relative angular displacement between the two components is not, but a second stage is, opposed by a load friction unit having a control plate which cooperates with at least two energy storing devices to oppose rotation of the one component with reference to the other component and/or vice versa.
Clutch plates of the above outlined character are disclosed, for example, in commonly owned German Pat. No. 2,436,288. FIG. 1 of this patent shows a clutch plate with a load friction generating unit having a control plate cooperating with two coil springs. The arrangement is such that the friction generating unit becomes effective practically instantaneously, namely, in abrupt response to completion of the first stage of angular displacement of the one component relative to the other component and/or vice versa. Also, the damping action of the friction generating unit remains unchanged for each and every increment of that stage of angular movement of the one and/or the other component during which the friction generating unit is effective. It has been found that the patented clutch plate solves many problems as regards the suppression of noise in the power train between the engine and one or more driven parts of an automotive vehicle or in any power train in which a clutch employing the patented clutch plate is put to use. It has further been found that the useful life of the patented clutch plate is longer than that of theretofore known clutch plates, as well as that the patented clutch plate reduces the likelihood of vibrations and/or other stray movements in a friction clutch or the like. However, it was also ascertained that the patented clutch plate fails to constitute an optimum solution of numerous problems which arise in certain categories of automotive vehicles, particularly in vehicles of the type wherein, in accordance with a rather recent proposal, the RPM of the engine during idling is much lower than in earlier engines. It was also found that heretofore known clutch plates (including the aforediscussed patented clutch plate) are not ideally suited for use in the clutches of automotive vehicles which, in accordance with certain recent proposals, are designed to save weight not only as far as the parts of the engine but also as far as other parts of the vehicle are concerned. Noise is also a problem which must be overcome or at least alleviated in such types of vehicles. It is assumed that one of the main reasons for the just enumerated problems is the irregular progress of RPM in such types of vehicles.